Function mysql_sql_stmt_execute_immediate

sql/sql_prepare.cc:2939–3015

static
bool mysql_sql_stmt_execute_immediate(THD *thd,
                                      bool dynamic_open_cursor,
                                      select_result *result_arg,
                                      Server_side_cursor **cursor_arg,
                                      const InstrSlice &instrs_set_placeholder)
{
  LEX *lex= thd->lex;
  CSET_STRING orig_query= thd->query_string;
  Prepared_statement *stmt;
  LEX_CSTRING query;
  DBUG_ENTER("mysql_sql_stmt_execute_immediate");

  /*
    Dynamic cursor placeholders are initialized from the USING clause
    with help of sp_instr_set_ps_placeholder instructions,
    so in case of a dynamic cursor lex->m_params should be empty.
  */
  DBUG_ASSERT(!lex->prepared_stmt.param_count() || !dynamic_open_cursor);
  if (lex->prepared_stmt.params_fix_fields(thd))
    DBUG_RETURN(true);

  /*
    Prepared_statement is quite large,
    let's allocate it on the heap rather than on the stack.

    It's important for "buffer" not to be destructed
    before stmt->execute_immediate().
    See comments in get_dynamic_sql_string().
  */
  StringBuffer<256> buffer;
  if (lex->prepared_stmt.get_dynamic_sql_string(thd, &query, &buffer) ||
      !(stmt= new Prepared_statement(thd)))
    DBUG_RETURN(true);                           // out of memory

  // See comments on thd->free_list in mysql_sql_stmt_execute()
  SCOPE_VALUE(thd->free_list, (Item *) NULL);
  SCOPE_EXIT([thd]() mutable { thd->free_items(); });
  /*
    Make sure we call Prepared_statement::execute_immediate()
    with an empty THD::change_list. It can be non empty as the above
    LEX::prepared_stmt_params_fix_fields() and LEX::get_dynamic_str_string()
    call fix_fields() for the PS source and PS parameter Items and
    can do Item tree changes, e.g. on character set conversion:

    - Example #1: Item tree changes in get_dynamic_str_string()
    SET NAMES utf8;
    CREATE PROCEDURE p1()
      EXECUTE IMMEDIATE CONCAT('SELECT ',CONVERT(RAND() USING latin1));
    CALL p1();

    - Example #2: Item tree changes in prepared_stmt_param_fix_fields():
    SET NAMES utf8;
    CREATE PROCEDURE p1(a VARCHAR(10) CHARACTER SET utf8)
      EXECUTE IMMEDIATE 'SELECT ?' USING CONCAT(a, CONVERT(RAND() USING latin1));
    CALL p1('x');
  */
  Item_change_list_savepoint change_list_savepoint(thd);